It is proposed during the next year to attack the problem of inhibition of gastric emptying along two fronts. Firstly, attempts will be made to localize in the duodenum and small bowel the receptors that are involved in inhibition of gastric emptying. These receptors are osmotic receptors, fat receptors, acid receptors, and tryptophan receptors. Dogs will be prepared with 3 gastric fistulas, one of which will be in the stomach and one will be in the duodenum at the junction of the first and the second parts of the duodenum and the other will be at the junction of the duodenum and jejunum. It is planned by using various combinations of test meals and perfusions, we will be able to selectively perfuse the first part of the duodenum, second to fourth parts of the duodenum, the whole duodenum, and the proximal jejunum. By these methods we will be able to determine whether inhibition of gastric emptying is caused by any of these agents when perfused into the selective site. From any inhibition that we find, we will be able to determine an inhibitory receptor lies in that area of the bowel or not. The second aspect of the project is concerned with neural control of gastric emptying. After control studies in simple gastric fistula cats and dogs, in which we will have infused various concentrations of osmotic substances, fats, acids, and tryptophan, the animals will undergo either a vagotomy or celiac ganglionectomy. Following these operative procedures, animals will be retested to determine what the effects of either or both of these operations have on gastric emptying. The adequacy of vagotomy will be determined by insulin test meals. If vagotomy is successful in inhibiting some of the inhibitory reflexes, then further studies will be done using selective and highly selective vagotomies.